For me it comes down to $$....from what I've seen looking for contract Mech. Design Engineer positions recently, with companies wanting 2000-4000 hours on any given system: SW brings about 25-35/hour. UG 40-50/hr. Catia 60-70/hr. Pro-E can be all over the place...25-40/hour. I came from UG to SW and found after about a week I was rolling. I tried Catia V5 and it is nothing like SW...steep curve but you can get things done if you follow the rules...very unforgiving....and the workbench methodology takes some getting used to. Pro-E I've not been on much at all except to convert some models before a change over. AutoCAD is just dumb unless you need to do Civil/Architectural type stuff... light 3d and 2d layouts. just my opinion.